Mehdi Zahravi * 
, Shaghayegh Shahveh , Reza Khaliliazar , Mehran Patpour , Shahpour Ebrahimnejad , Mohammadreza Bihamta
, Shaghayegh Shahveh , Reza Khaliliazar , Mehran Patpour , Shahpour Ebrahimnejad , Mohammadreza Bihamta
Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Abstract: (16 Views)
Powdery mildew is one of the most important diseases of barley. However, many resistance genes have become ineffective due to shifts in pathogen populations and the emergence of new virulent races. Therefore, identifying genes that provide effective resistance against the pathotypes of this disease is of significant importance. In this study, pathogen isolates were first collected from various regions of the country. The collected isolates were propagated, purified, and inoculated onto a set of isogenic lines carrying different resistance genes. The responses of the isogenic lines to the studied pathotypes revealed considerable variation in both the resistance of the isogenic lines and the virulence of the pathotypes. The infection type ranged from 2 to 4 across different pathotypes, and the coefficient of variation ranged from 19.35% to 62.83%. Among the evaluated genes, mlo5 exhibited the highest level of effectiveness, followed by Mla9 and Mla13+Ml(Ru3), which also demonstrated substantial effectiveness. Principal component analysis indicated that the first five principal components accounted for 85.17% of the total variation in the data. Cluster analysis grouped the resistance genes into four distinct clusters. The findings highlight the high diversity and dynamic nature of the powdery mildew pathogen population in the country, underlining the importance of continuous monitoring. Moreover, the resistance genes were evaluated and compared based on their effectiveness, providing insights for their application in breeding programs tailored to specific regions. Among the resistance genes evaluated, mlo, Mla9, and the gene combination Mla13+Ml(Ru3) exhibited higher effectiveness. Each of these genes can be incorporated individually into breeding programs, or alternatively, a gene pyramiding approach may be employed. In addition, the resistance genes Mla9, Mla22, Mla1, and Mla7+Ml(No3) are recommended for use in the Sari region, whereas Mla9, Mla13+Ml(Ru3), and Mla7+Ml(No3) are recommended for the Gorgan region. Conversely, the gene combination Mla12+Ml(Em2) and the resistance gene Mlh were identified as ineffective; therefore, it is recommended that their use be avoided or that appropriate precautionary strategies be adopted in this regard.
Article number: 4
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